Add unit test doc

[syamgk]

Add Unit test documentation to deployment.md

[ashetty1]

Can we put links in markdown format instead?

[ashetty1]

I think the tense for the entire document should be simple present tense.

[ashetty1]

Remove basically

[ashetty1]

Just "Writing unit tests" should be fine ...

[ashetty1]

Would be good to have example code for each of these points.

Also, bullet/number them.

[ashetty1]

Use [](url)

[syamgk]

thought explicit will be better but will go with hyperlink

[ashetty1]

I think instead of using RemoveVolumeFromDeploymentConfig which internally calls GetDeploymentConfigFromName, we should have examples of functions which directly make create, list and get calls.

[ashetty1]

We need more description for this section explaining the concepts like reactor, actions, verb in more detail. We could work together on this.

[cdrage]

What'st he status of this @syamgk ?

[syamgk]

@cdrage incorporated the comments and ready for next round of review

[anmolbabu]

convert fake itself into a clickable link as in https://github.com/redhat-developer/odo/pull/673/files#diff-6fede6782d33a3306a99cb1a47ea5f6bR23

[anmolbabu]

same here

[anmolbabu]

It can be observed that, the function CreateRoute above is making 1 api call as in the line below:

r, err := c.routeClient.Routes(c.namespace).Create(route)

[anmolbabu]

Would it be ok to shorten the description as under:

From the API call extract above, it is clear that the routeClient needs to be mocked.
The mock routeClient can be obtained using pkg/occlient/fakeclient.go#FakeNew function.

It is done as under:

code here...

Note:
The FakeNew function contains mock implementations of all client sets currently in use by Odo
If the mock implementation of a client set that you are using does not exist, please add it as under:

fkclientset.RouteClientset = fakeRouteClientset.NewSimpleClientset()
client.routeClient = fkclientset.RouteClientset.Route()

[anmolbabu]

Ideal list of items to validate in the unit test function are:

• Number of actions performed or number of api calls made using the client set
  ex : len(fkclientset.RouteClientset.Actions())
• Validate the return values of the function being tested
  ex: here

[anmolbabu]

Please move this above I feel it would be nice if we could group all mocking together, all validations together etc..

and would it be nice to rephrase it as under:

Mock the api call return values using reactor functions here

[anmolbabu]

I think it would be nice to convert all(as much as possible) all github links to markdown links and not expose the github urls(Github urls seem very ugly to me from the perspective of a reader :) but yes this for a special reader -- A DEVELOPER :P but still I feel it would be nice to avoid it)

[anmolbabu]

If possible can we pick one single example that covers all aspects of testing and only consider that throughout the doc?
Not a very crucial thing to be done, but I feel it would avoid context switches in reader's mind

[anmolbabu]

May be call this section as Terminologies or something?

[ashetty1]

Unit tests

Introduction

Unit-tests for ODO functions are written using package fake. This allows us to create a fake client, and then mock the API calls defined under OpenShift client-go and k8s client-go.

The tests are written in golang using (pkg/testing)[https://golang.org/pkg/testing/] package.

Writing unit tests

1. Identify the APIs used by the function to be tested.

2. Initialise the fake client along with the relevant clientsets.

3. In the case of functions fetching or creating new objects through the APIs, add a reactor interface returning fake objects.

4. Verify the objects returned

Initialising fake client and creating fake objects

Let us understand the initialisation of fake clients and thereafter creation of fake objects with an example.

The function GetImageStreams in pkg/occlient.go fetches imagestream objects through the API:

func (c *Client) GetImageStreams(namespace string) ([]imagev1.ImageStream, error) {
        imageStreamList, err := c.imageClient.ImageStreams(namespace).List(metav1.ListOptions{})
        if err != nil {
                return nil, errors.Wrap(err, "unable to list imagestreams")
        }
        return imageStreamList.Items, nil
}

1. For writing the tests, we start by initialising the fake client using the function FakeNew() which initialises the image clientset harnessed by GetImageStreams funtion:

   client, fkclientset := FakeNew()

2. In the GetImageStreams funtions, the list of imagestreams is fetched through the API. While using fake client, this list can be emulated using a PrependReactor interface:

    fkclientset.ImageClientset.PrependReactor("list", "imagestreams", func(action ktesting.Action) (bool, runtime.Object, error) {
        	return true, fakeImageStreams(tt.args.name, tt.args.namespace), nil
        })
   

   The PrependReactor expects resource and verb to be passed as arguments. We can get this information by looking into List function for fake imagestream:

   func (c *FakeImageStreams) List(opts v1.ListOptions) (result *image_v1.ImageStreamList, err error) {
       	obj, err := c.Fake.Invokes(testing.NewListAction(imagestreamsResource, imagestreamsKind, c.ns, opts), &image_v1.ImageStreamList{})
   	...
       }
       
   func NewListAction(resource schema.GroupVersionResource, kind schema.GroupVersionKind, namespace string, opts interface{}) ListActionImpl {
       	action := ListActionImpl{}
       	action.Verb = "list"
       	action.Resource = resource
       	action.Kind = kind
       	action.Namespace = namespace
       	labelSelector, fieldSelector, _ := ExtractFromListOptions(opts)
       	action.ListRestrictions = ListRestrictions{labelSelector, fieldSelector}
   
       	return action
   }
   
   
   

The List function internally calls NewListAction defined in k8s.io/client-go/testing/actions.go. From these functions, we see that the resource and verbto be passed into the PrependReactor interface are imagestreams and list respectively.

You can see the entire test function TestGetImageStream in pkg/occlient/occlient_test.go

[ashetty1]

@syamgk see if you can use the blurb for this PR.

@cdrage you review would be valuable :)

[cdrage]

ODO needs to be Odo.

[cdrage]

ODO needs to be Odo.

[cdrage]

using the

[cdrage]

therefore the creation of fake objects with an example.

[cdrage]

you need to make it:

```go

wherever there is go code to be shown.

[cdrage]

```go

[cdrage]

passed in as arguments

[cdrage]

by looking at the

[cdrage]

```go

[cdrage]

you forgot to end this with 3 `

[cdrage]

space after verb

[cdrage]

interface are imagestreams and list functions.

[cdrage]

This LGTM 👍 I'm going to merge this in. (only 1 ACK needed for docs)